Vapor-liquid phase conversion



1960 F. w. VAN LUlK, JR 2,962,265

VAPOR-LIQUID PHASE CONVERSION 2 Sheets-Sheet 1 Filed Oct. 22, 1956 f)?Mental" fi'am M Van!) 0/16,

Nov. 29, 1960 Filed Oct. 22, 1956 F. w. VAN LUIK, JR 2,962,265

VAPOR-LIQUID PHASE CONVERSION 2 Sheets-Sheet 2 T/IIZ/Y/IVUTITifiPI/PATUI! a" QRRRG$ Q 5am? MVa/zm. J1;

United States Patent VAPOR-LIQUID PHASE CONVERSION Frank W. Van Luik,Jr., Schenectady, N.Y., assignor to General Electric Company, acorporation of New York Filed Oct. 22, 1956, Ser. No. 617,371

8 Claims. (Cl. 257-43) This invention relates to a method and apparatusfor vapor-to-liquid phase conversion. More particularly, it relates to amethod and apparatus for increasing steam condensation rates.

Vapor-to-liquid phase conversion systems are of great importance in manyindustrial as well as household areas. Thus, turbine power plants,refrigeration systems, distilling processes, chemical processes,household appliances such as dishwashers, represent but a fragmentaryrecital of their utility. In all such systems it is desired, at somestage, to convert a vapor into a liquid condensate. Probably one of themost important and well known of the applications listed above is steamcondensation in a turbine power plant system. In such a system it isdesired to change the steam vapor coming from the turbine into acondensate; this process taking place in a piece of apparatus called,aptly enough, a condenser.

Such steam condensers may be either of the direct contact type or of thesurface type. That is, condensation is either by direct contact betweenthe vaporized steam and water, as in the case of the so-called jetcondensers; or by surface condensation, where a wall of metal acting asa heat transfer surface prevents the mixing of the steam and the coolingmedium. In a surface condenser of the water cooled type, water flowsthrough a series of tubes positioned within the condenser, and steam iscondensed by being brought into contact with the outside of the tubeswhich act as heat transfer surfaces. For condensation to take place atthe heat transfer surfaces, it is necessary that either one of twoconditions be pres out; that is, either condensation nuclei must beprovided within the condenser, or the relative humidity within thecondenser must be raised to an extremely high value, (around 400%) sothat the vapor will condense spontaneously.

' In present practice, condensation nuclei within the condenser must beprovided by impurities on the heat transfer surfaces or by straycondensation nuclei present within the condenser due to air leakagearound flanges, gaskets, and so forth. These prior art steam condensers,which utilize the randomly positioned condensation nuclei on the heattransfer surface and the accidental leakage introduced nuclei, leavemuch to be desired in supplying condensation nuclei in sufiicientquantities to provide for increased condensation rates with given heattransfer surface areas.

Condensation nuclei is a generic name given to small particles which arecharacterized by the fact that they serve as the nucleus on which water,for example, will condense to produce droplets. Such condensation nucleiencompass microscopic and submicroscopic particles, the most importantsegment of the size spectrum lying in a size range extending fromapproximately 2.5 X10 cm. radius to 1X10 cm. radius. It has beenobserved that during electrical arcing phenomena an extremely highconcentration of condensationnuclei is present in the vicinity of theare. It is beice lieved that when an electric arc is formed theextremely high temperatureabout 3000 K.present in the arc vaporizes thecontact or electrode material and causes it to be diffused into the airsurrounding the contact elements. This vaporized material'cools rapidlyand results in the creation of a large number of extremely minuteparticles only a few angstroms in radius (1 angstrom=l0- cm.). Thenumber of particles produced per discharge may run in the order of 10These particles immediately start recombining by collision. Thisrecombination rate is extremely rapid and is a function of the square ofthe number of particles present and of their average kinetic energy. Inonly a few microseconds, the major portion of the particles havecollided one or more times and recombined to form larger particles. Thisrecombination process continues and the average particle becomes of theorder of magnitude of 10- cm. radius. Thus, after a few milliseconds theair surrounding the electrodes between which the arc discharge tookplace contains several million particles ranging in size from 10* to 10-cm. radius with the largest number in the range of 10- to 10" cm.radius. These metallic particles produced by an electrical arc dischargeact as condensation nuclei and may be utilized as a convenient sourcethereof.

By utilizing a condensation nuclei source of this, or similar, type andinjecting the condensation nuclei thus produced into the vapor space ofa steam condenser, it becomes possible to increase the condensation rateof such an apparatus substantially.

It is an object of this invention, therefore, to provide a method andapparatus for substantially increasing the rate'of vapor-to-liquid phaseconversion.

A further object of this invention 'is to provide a method and apparatusfor increasing the rate of vaporto-liquid phase conversion utilizingcondensation nuclei injection.

Yet another object of this invention is to provide a vapor condensationapparatus in which condensation occurs in the vapor space as well as ata heat transfer surface.

Still another object of this invention is to provide a steam condenserhaving an increased condensation rate including condensation nucleiinjecting means to permit condensation in the condenser vapor space aswell as at the heat transfer surface.

Further objects and-advantages will become apparent as the descriptionof this invention proceeds.

In accordance with this invention, there is provided a steam condenserof standard configuration having a condensaton nuclei source positionedtherein which periodically injects a quantity of nuclei into the vaporspace of the condenser. By thus causing condensation of the steam in thevapor space as well as at the surface of the water cooled heat transfersurfaces, the rate of condensation is increased for a given amount ofheat transfer surface. In a preferred embodiment the condensation nucleisource is shown as an arc discharge between tWo spaced electrodeelements. In an alternative embodiment solenoid operatedcontact elementsmay be utilized to produce the electrical arc discharge which forms thenecessary condensation nuclei.

The novel features which are believed to be charac teristic of thisinvention are set forth with particularity in the appended claims. Theinvention itself, however, both as to its organization and method ofoperation, together with further objects and advantages thereof, maybest be understood by reference to the following description taken inconnection with the accompanying drawings in which:

Fig. 1 shows a view partially in cross-section of a Patented Nov. 29,1960 steam condenser embodying the novel features of the invention;

Fig. 2 is an enlarged view of a portion of Fig. 1;

Fig. 3 is an alternative embodiment of the structural featureillustrated in Fig. 2; and

Figs. 4 and 5 are graphs illustrating the effects of nuclei injection.

Referring now to Fig. 1, there is shown a preferred embodiment of avapor-to-liquid phase conversion apparatus, of the steam condenser type,illustrating the principles of the instant invention. There is provideda chamber means 1 adapted to hold a vaporized liquid such as steam. Saidchamber comprises a tubular shell member 2, shown in cross-section,constituted of welded steel and reinforced against collapsing pressure.Positioned at the top of the condenser shell 2 is a steam inlet conduit3 for introducing the steam vapor at a reduced pressure into thecondenser proper. The steam inlet conduit 3 may be connected to theexhaust piping of a turbine, not shown, by means of a flexibleconnection such as an ex pansion joint or a packing box. Positionedalong the lower periphery of the condenser shell 2 and communicatingtherewith are a pair of conduits 5 arranged to be connected to airpumps, not shown, to remove any uncondensed steam and air residue in thecondenser. An outlet 6 is provided at the bottom of the condenser topermit flow of condensate out of the condensing apparatus.

Positioned within the condenser shell 2 are heat transfer surfacesdesigned to abstract heat from the steam to induce at least a portion ofthe steam to condense thereon. To this end there are provided amultiplicity of hollow metallic tubes 7 extending axially along thelength of the condenser shell and adapted to have cooling water flowingtherethrough. A pair of conduits 8 provide a cold water inlet, while apair of conduits 9 positioned near the top of the condenser provide aWarm water exit for the cooling water flowing through the tubes 7. Boththe conduits 8 and 9 as well as the heat transfer tubes 7 are connectedto a water box or header, not shown, posi tioned at one end of thecondenser apparatus to provide a chamber in which the cooling water maybe introduced, caused to pass through the heat transfer tubes 7, andthen withdrawn by means of the warm water exit conduits 9. In thisfashion a continuous flow of cooling water is occasioned through thetubes 7 establishing a temperature differential between the tube surfaceand the steam within the chamber 2. Hence, the tubes 7 act as a heattransfer surface, and in conjunction with condensation nuclei present attheir surface, cause condensation of the steam within the chamber.

There is provided a source of condens tion nuclei for periodic injectionof nuclei into the vapor space of the condenser 1 in order to occasioncondensation of the steam in the vapor space as well as at the heattransfer surfaces. To achieve these results, electrical are dischargecondensation nuclei sources 10 are positioned within the condenser shell2 to provide a supply of nuclei. The specific configuration of thecondensation nuclei source may be most easily seen with reference toFig. 2 which is an expanded fragmentary view of a portion of Fig. 1. Thecondensation nuclei source 10 comprises a terminal board 11 fastened tothe chamber wall 2 by means of bolts or any other similar fasteningmeans. Mounted on the terminal board 11 are a pair of standoffinsulators 12 of the ceramic or porcelain type having conductors 13extending th'erethrough to constitute a pair of spaced dischargeelectrode elements 14 forming a discharge gap. The conductors 13 areconnected to a source of energizing voltage through a pair of insulatingbushings 15 extending through the chamber wall 2. This source of voltageprovides the energization for periodically causing a nuclei producingspark discharge between the electrodes 14 and consists of a high voltagestep-up transformer 16 of the iron core type. The transformer 16 has aprimary winding 17 and a secondary winding 18. The primary winding 17 isconnected to a source of alternating voltage 19, not shown, which may bea standard v. 60-cycle power line. The secondary winding 18, which isconnected to the conductors 13, contains a very large number of turnsand steps up the 115 volts applied to the primary to a voltagesufficiently large to cause an arc discharge between the electrodes 14.Thus, for example, the construction of the transformer 16 may be suchthat the voltage across the secondary winding 18 is stepped up to 2000volts at 60 cycles. Hence, there is applied to the electrodes 14 avoltage of sufficient magnitude to cause an arc discharge whichgenerates condensation nuclei constituted of small particles ofelectrode material. Since the voltage applied to the electrodes 12 is analternating voltage having a repetition frequency of 60 cycles persecond, there will be produced discharges per second each of whichproduces a large number of condensation nuclei to aid in thecondensation rate of the steam.

Surrounding electrodes 14 and the discharge gap is a hollow, slittedtubular member 20, which prevents the diffusion of the vaporized contactmaterial into the air, and assures that this vaporized materialrecombines into fairly large condensation nuclei by maintaining theseparticles in close proximity to each other and increasing therecombination probability. In this fashion, it is possible, to a certainextent, to control the size of the condensation nuclei which will beinjected into the condenser vapor space, and in turn the efficiency ofthe process.

An alternative embodiment of the condensation nuclei source of Figs. 1and 2 is illustrated in Fig. 3. This alternative condensation nucleisource comprises an electromagnetic relay in which a pair of contactsare periodically operated to produce condensation nuclei by means ofelectrical arcing. The condensation nuclei source 10 illustrated in Fig.3 comprises a terminal board 31 fixedly mounted on the condenser wall 2.Positioned at the top of the terminal board 31 are a number of terminals32, 33, 34, and 35. The terminal 32 is electrically connected to a fixedcontact member 36 positioned on the terminal board 31 while the terminal35 is connected to a spring biased armature member 38 having a contactelement 37 mounted thereon. A solenoid element 39 positioned injuxtaposition with the armature member 38 is positioned on the terminalboard 31 and actuates the armature member 38 to operate the contactelements 36 and 37 periodically. The solenoid coil 39 has a pair ofoutput leads connected to the solenoid terminals 33 'and 34.

The terminals 32, 33, 34, and 35 are connected, through an insulatingbushing 40 extending through the condenser wall, to a pair of externalelectrical circuits 41 and 42 which function respectively to operate thesolenoid relay 39 and to provide a load circuit for the contactelements. Contact terminals 32 and 35 are connected to a load circuit 41comprising a load'element 43 to cause flow of current through thecircuit when the contacts 36 and 37 are closed.

Terminals 33 and 34 are connected to a solenoid actuating circuit 42which functions to energize the solenoid periodically in order tooperate the contact elements. The solenoid circuit 42 comprisesa pair ofterminals 46 connected to a source of suitable voltage for operating thesolenoid coil 39. This energy is periodically applied to the coil bymeans of a microswitch and timing arrangement. A contact element 44,which may be a microswitch or the like, is connected in series in onelead extending between the solenoid coil 39 and one of the voltageterminals 46. A timing mechanism 45, which may be a cam member or thelike, is mechanically coupled to the contact member 44 and periodicallycloses the contacts. Upon closing of the contacts 44, a circuitconnection is made between the source of energy applied at the terminals46 and the solenoid 39 energizing the solenoid and actuating the contactmembers 36 and 37.

The timing mechanism 45 may be adjusted to provide any desired frequencyof operation. In this manner the contact elements within the condensermay be operated at any desired frequency to produce an adequate supplyof condensation nuclei to be utilized in increasing the condensationrate of the steam within the condenser.

- While it is not intended that the scope of the invention be limited byany particular theory of operation, it is believed that the followingmechanism takes place within the condenser by the injection ofcondensation nuclei into the vapor space. Steam at reduced pressure,which in some cases may be as low as two inches of mercury, is broughtinto the condenser via the steam inlet conduit from a turbine or othersimilar device. The incoming steam is at saturation for the steamtemperature at the particular pressure. Thus, at two inches of mercurypressure the steam temperature at saturation would be 101 F. Theincoming steam flows over the heat exchange surfaces represented by thetubes 7 which, being traversed by cooling water, are naturally at alower temperature than the incoming steam. Should the incoming steam besuper-heated to any extent, the passage of the steam across the heattransfer surfaces removes whatever degree of super-heat is present. Thesteam in the condenser chamber continues to lose heat to the heattransfer surfaces and consequently the steam keeps cooling until itbecomes super-cooled and consequently supersaturated. At this stage,condensation begins about any nuclei present at the surface of the tubesand a film of water begins forming thereon which, as time progresses,drips off the tubes and out of the condenser through the condensateexit.

Up to this point, the condensing mechanism has been described withoutconsidering the injection of additional condensation nuclei into thecondenser vapor space. If,

now, a quantity of condensation nuclei, several orders of magnitudegreater than the number normally present, is injected into the condenservapor space between the heat transfer surfaces, condensation of thesteam about these nuclei will occur within the vapor space. Suchcondensa tion is in addition to that taking place at the heat transfersurface which normally occurs in all condensers. The formation of waterdroplets in the vapor space occasioned by condensation about the nucleicauses a release of heat in the space from the conversion from the vaporto the liquid stage. This heat is partially absorbed by the dropletsformed within the chamber, but a portion of it is transferred to theheat transfer surface across the boundary water film. This is believedto occur since the addi tional heat given off in the vapor chamber bycondensation in the vapor space increases the temperature differentialbetween condenser vapor space and the heat transfer surface. Thus, agreater amount of heat is transferred across the surfaces for a givensurface area.

In addition, it is though that the droplets formed in the vapor space bythe injection of the condensation nuclei strike the heat transfersurfaces in falling and lose a portion of their heat to those surfaces.However, in striking the heat transfer surfaces in this manner, the filmof liquid at the heat transfer surface is ruptured so that drop-wisecondensation is effectively achieved. As is well known, theheat transfercoefficient for drop-wise condensation on a heat transfer surface ismuch larger; on the order of four times, than that for film-wisecondensation. It is believed that this manner of condensing dropletswithin the vapor space in addition to that occurring at the heattransfer surface causes drop-wise condensation-and thus permits anadditional removal of heat by the heat transfer surface.

byestablishing agreater temperaturedifierential between the .vapo-rspace and the heat transfer surface .due. to the heat of condensationgiven off, and dueto the improved heat transfer coeflicient achieved bymeans of the BEE Q1;f3-IQRTYYF a enset pi a .sub teqti limprove- 8 mentin the condensation rate for-a given heattransfer surface is achieved byvirtue of the instant invention.

It is clear that if the injection of condensation nuclei into the vaporspace actually increases the rate of steam condensation for a given heattransfer surface that two specific effects should be observed. First,the amount and temperature of the condensate per unit time for any fixedhead of steam should increase with the injection of condensation nuclei.That is, if condensation is taking place in the vapor space in additionto that occurring at the heat transfer surface, obviously, a greateramount of condensate should be present per unit time during the periodof such injection. Furthermore, the temperature of the condensate shouldincrease since, as was pointed out before, the additional dropletscondensing in the vapor space give off heat of condensation which ispartially absorbed by the droplets thus formed within the vapor space.Secondly, the temperature differential of the cooling water should showan increase since, as was pointed out previously, both an increasedtemperature differential as well as drop-wise condensation is believedto occur which increases the amount of heat abstracted from the chamberby means of the heat transfer surface.

In order to establish the validity of the nuclei injection technique inincreasing the rate of steam condensation, a series of experiments wererun which demonstrate the relationship of the quantity of condensateproduced for a given time period with nuclei injection and withoutnuclei injection. Furthermore, another series of tests was run todetermine the eir'ectson the cooling water temperature and on thecondensate temperature of the injection of nuclei into the vaporchamber. The experi-' ments bearing on the amount of condensate producedin a given period of time with and without condensation nuclei injectionbrought the following typical results which are tabulated as follows:

Cooling Condensate Condensate Test Water ec./l0 min. ce./l0 min. PercentccJmin. Before During Increase Arcing Arcing The above data clearlyindicates that the provision of condensation nuclei injection meanswithin a steam condenser caused a substantial increase in the amount ofcondensate produced within a fixed time period. Clearly then,condensation nuclei injection means in a vapor-toliquid phase conversiondevice such as a steam condenser provides substantial increase in theoperating efficiency of the device.

The results of the experiments to determine temperature changes in thecooling water and in the condensate are best illustrated by means of thegraphs of Figs. 4 and 5 which clearly show the effects on thetemperature of the injection of condensation nuclei. Referring now toFig. 4, there is shown a graph inwhich time is plotted along theabscissa whereas temperature is"plotted along the ordinate. The graph ofFig. 4 illustrates twocurve's denominated at T-l and T-2. The curve T-lshows'the results of a number of temperature measurements at the coolingwater inlet of the condenser whereas the curve T-Z illustrates thetemperature at the warm water outlet of the condenser. The curves T-1and T4 are sub.- divided into three distinct portions: a, b, and c.Portions g and b being the times during which nocondensatio'n nuclei arebeing injected into the vapor. chamber, whereas portion 11refiectsIdata-during a period of tiniewhen condensation nuclei areinjected into the vapor chamber by m aasqt an les al As c n ,beseeniromFig. 4, the temperature at the cooling water inlet T- l doesnot changewith the injection of condensation nuclei, which is as it should besince this temperature is the temperature of an external source ofcooling water being brought into the condenser at a constant rate. Thecurve T-2 indicates quite clearly, however, that the initiation ofnuclei injection into the chamber causes a fairly substantial rise inthe temperature of the cooling liquid as measured at the exit conduit.This indicates that a greater quantity of heat is transferred from thecondenser chamber to the cooling liquid during the period whencondensation nuclei are injected into the chamber than during the periodwhenno nuclei injection takes place. This would seem to indicate thateither a greater temperature differential exists between the vaporchamber and the heat transfer surface during nuclei injection or that abetter heat transfer coefficient is achieved during this period, orboth, since experimentation has shown that the heat added from the arcitself cannot account for the observed temperature rise. Thus, theresults of the experiments illustrated in the graph of Fig. 4 seem tobear out the hypothetical condensation mechanism proposed in the earlierexplanation.

Fig. 5 is a graph similar to that of Fig. 4 with the exception that anadditional curve showing the temperature of the condensate is plottedthereon. That is, once more time is plotted on the abscissa whiletemperature is plotted along the ordinate. Similarly, curve'T-lillustrates the temperature at the cooling water input, T4 thetemperature at the warm water output conduit, while curve T-cillustrates the temperature of the condensate produced during variousperiods. Again, it can be seen from Fig. 5 that the temperature of thecooling Water at the warm water exit conduit rises substantially withnuclei injection into the water vapor space. Similarly the curve T'cindicates the temperature of the condensate rising substantially duringthe period of nuclei injection. These curves thus seem to buttress thehypothesis put forward previously. That is, that the injection of thenuclei produces additional heat of condensation which is reflected bothin the temperature of the cooling liquid as well as of the condensate.

Hence, it can be seen from these experimental results that the principleof nuclei injection into a vapor-to-liquid phase conversion systemprovides a very effective and powerful tool for increasing the rate ofconversion of such processes without simultaneously having to increasethe heat transfer surface as was previously believed to be necessary.Thus, a very effective tool has been presented to designers of suchequipment by means of which great improvements in the efiiciency of suchapparatus may be achieved.

In the preceding description, the condensation nuclei producing andinjecting source has been described and illustrated as an electricalarcing source which, by means of the arcing, produces condensationnuclei. It is to be understood, however, that although electrical arcingsystems are the preferred embodiments of a condensation nuclei injectionsource, that many other possible condensation nuclei sources may beutilized with this invention. Thus, combustion products, vaporization ofsalt, liquid sprays, metallic carbonyis, dust sprays, as wellasconversion of gases such as SO- by means of ultraviolet light, maybeutilized as condensation nuclei. Thus, the particular condensationnuclei source utilized will be determined by its applicability andfeasibility in a particular piece of equipment.

In the preferred embodiments illustrated in Figs. l3, the condensationnuclei sources are shown mounted within the condensation chamber 2. Itis obvious, however, that the nuclei sources may be positioned externalto the chamber and nuclei injected into the vapor space by nucleisources other than electrical, such as those enumerated in the precedingparagraph are utilized, injection by means of such conduits would bepreferable.

In a similar fashion, the instant invention has been described primarilyin connection with a steam-to-water condenser as the example of thevapor-to-liquid phase conversion. It is obvious, of course, that manyother areas of utilization besides steam condensers for turbines arepossible for the instant invention. Thus, this condensation nucleitechnique is obviously applicable to distillation processes,refrigeration processes, drying chambers of dishwashers, as well as manyother similar processes in which a vapor-to-liquid phase transition isbrought about.

Fluids other than water may, of course, be converted from the vapor tothe liquid phase by means of condensation nuclei. Thus, for example,vaporized oil may be converted to its liquid phase by means of thisinjection technique. In a like manner, refrigerants such as freon or thelike are susceptible to this type of phase conversion.

From the foregoing description, it can be appreciated that the instantinvention provides an apparatus and method for increasing the conversionrate of vapor-toliquid phase transitions such as steam condensation.

While a particular embodiment of this invention has been shown it will,of course, be understood that it is not limited thereto since manymodifications both in the circuit arrangement and in theinstrumentalities employed may be made. It is contemplated by theappended claims to cover any such modifications as fall within the truespirit and scope of this invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In a vapor-to-liquid phase converting apparatus, the combinationcomprising chamber means adapted to hold a saturated vaporized liquid,heat transfer surface means positioned within said chamber means toeffect the condensation of at least a portion of the vapor at saidsurface, periodically actuated electrical are producing means positionedin said chamber for injecting particles formed by said are producingmeans into the chamber vapor space, said injected particles acting ascondensation nuclei to produce additional condensation of the saturatedvapor in said chamber vapor space whereby the condensation rate isincreased.

2. In a vapor-to-liquid phase converting apparatus, the combinationcomprising chamber means adapted to hold a-saturated vaporized liquid,heat transfer surface means positioned within said chamber means toeffect the condensation of a portion of the vapor at said surface,electrical are means including spaced arc discharge electrodespositioned in said chamber, said arc means producing additionalcondensation nuclei from the arc erosion particles to produce additionalcondensation in said chamber space whereby the condensation rate isincreased.

3. In a vapor-to-liquid phase converting apparatus, the combinationcomprising chamber means adapted to hold a saturated vaporized liquid,heat transfer surfaces vpositioned within said chamber means to effectcondensation of a portion of the vapor at said surfaces, periodicallyoperated electrical are producing contact means positioned within saidchamber providing condensation nuclei to produce additional condensationin the chamber vapor space whereby the condensation rate is increased.

4. In a vapor-to-liquid phase converting apparatus, the combinationcomprising chamber means adapted to hold a saturated vaporized liquid,heat transfer surfaces positioned with said chamber means to effectcondensation of a portion of the vapor at said surfaces, electrical arepro ducting contact means positioned within said chamber to injectcondensation nuclei formed from the erosion products of said arcproducing means into the chamber vapor space and produce additionalcondensation, actuating means for operating said contacts periodicallywhereby the condensation rate is increased.

'5. Inavapor-to-liquid phasecouversion apparatus, the

combination comprising chamber means adapted to hold a saturatedvaporized liquid, heat transfer surfaces positioned with said chambermeans to efiect condensation of a portion of the vapor at said surfaces,spaced electrodes forming an arc producing discharge gap positionedwithin said chamber to inject condensation nuclei formed from arcerosion products into the chamber vapor space whereby the condensationrate is increased.

6. In a steam condensing apparatus, the combination comprising a chamberadapted to hold saturated steam, heat transfer surfaces including amultiplicity of cooling fluid containing hollow members to effect thecondensation of a portion of the steam at said surfaces, electricalcontact means positioned within said chamber to inject condensationnuclei into the chamber vapor space to produce additional condensationto increase the condensation rate, and actuating means for operatingsaid contacts periodically.

7. In a method for increasing the rate of vapor to liquid phasetransition, the steps comprising introducing a saturated vapor into acondensing chamber, extracting heat from said vapor to initiatecondensation, injecting additional condensation nuclei into theremaining vapor for producing additional condensation of vapor about the10 nuclei including the step of producing electrical are discharges toproduce the additional nuclei.

8. In a method for increasing the rate of vapor to liquid phasetransition in a steam condensing system, the steps comprisingintroducing saturated steam into a condensing chamber, extracting heatfrom said steam to initiate condensation, injecting additional nucleiinto the remaining steam for producing additional condensation of saidsteam including the step of producing periodic electrical arc dischargesto produce the nuclei forming arc erosion particles.

References Cited in the file of this patent UNITED STATES PATENTS1,053,133 Potts Feb. 11, 1913 1,103,490 Cordray July 14, 1914 1,835,557Burke Dec. 8, 1931 1,928,963 Chaffee Oct. 3, 1933 2,052,626 HoughtonSept. 1, 1936 2,368,421 Meyer Jan. 30, 1945 2,514,797 Robinson July 11,1950 2,527,230 Schaefer Oct. 24, 1950 2,550,324 Brandau Apr. 24, 19512,606,270 Vonnegut Aug. 5, 1952 2,664,274 Worn et al. Dec. 29, 1953

